Field of the Invention
Various embodiments relate to a method for determining a position of a receiver and a corresponding positioning system. In particular, various embodiments relate to techniques which enable a determination of the position of the receiver via rotating magnetic fields.
Description of the Background Art
Techniques are known which enable localization, i.e., position determination, for example of identification transmitters. One example of an identification transmitter would be a key for a motor vehicle; indeed, techniques are known which make it possible to determine the position of the key in the surroundings of the motor vehicle in order to achieve access control for the motor vehicle. Conventional techniques are typically based on a measurement of a field intensity of an electromagnetic field emitted from a centralized transmitter. Since the field intensity decreases as the distance to the transmitted increases (attenuation or dwindling of the field intensity), it is possible to deduce a position in relation to the transmitter from a measurement of the field intensity using a receiver antenna in the key.
However, such techniques can have limited accuracy in terms of determining the position of the identification transmitter, for example due to limited accuracy in the measurement of the field intensity. In known systems, typical accuracies for position determination are 10-20 cm, for example. What is more, systematic distortions can occur: particularly, the reduction in the field intensity of the electromagnetic field can be interfered with by magnetic objects, for example, such as the vehicle body, etc., so that the determination of the position of the identification transmitter can be fraught with certain systematic errors. Such cases can make it necessary to perform a one-time manual measurement of the dwindling of the field intensity in and around the motor vehicle in order to calibrate the position determination. Such manual measurement can be time-consuming, resulting in commensurate costs. The calibration itself can even open up possible sources of error.
Above, the disadvantageous effects of the prior art in relation to the techniques of position determination itself were explained. However, disadvantageous effects can also arise in relation to the system architecture of corresponding devices, as will be explained below. Previously known positioning systems for position determination typically have a central control device which is connected by means of supply lines to the individual transmitters emitting the electromagnetic field. However, the provision of supply lines for the plurality of transmitters, typically three to five, can take up installed space in the motor vehicle and necessitate time-consuming and expensive cabling with two or four-wheeled lines, for example. Moreover, such systems often have only a small degree of modularity, since it is not readily possible to operate the system functionally with a smaller or larger number of transmitters, thus limiting the possibilities for the provision of different equipment options. What is more, the corresponding system can be relatively susceptible to faults, since a power outage or a malfunction of the central control device often can result in a complete breakdown of the system.
For the abovementioned reasons, there is a need for improved methods and systems for determining the position of a receiver. Particularly, there is a need for methods and systems which enable an especially accurate position determination while simultaneously having a low proneness to faults with a simple and cost-effective system architecture.